\(3\left(x-\dfrac{1}{2}\right)-5\left(x+\dfrac{3}{5}\right)=-x+\dfrac{1}{5}\)
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\(\dfrac{x-1}{5}+\dfrac{x+1}{7}+\left(x-1\right)\left(x+1\right)=\left(x+1\right)^2\)
\(\Leftrightarrow\dfrac{7\left(x-1\right)+5\left(x+1\right)}{35}+x^2-1=x^2+2x+1\)
\(\Leftrightarrow\dfrac{12x-2}{35}=2x+2\)
\(\Leftrightarrow\dfrac{6x-1}{35}=x+1\)
\(\Leftrightarrow35x+35=6x-1\)
\(\Leftrightarrow x=-\dfrac{36}{29}\)
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Còn lại số quả cam là:
105 x 1/5 = 21 ( quả)
Đáp số:..............
Số quả cam bà bán đi là:
105 x 1/5 = 21 (quả)
Số quả cam còn lại là:
105 - 21 = 84 (quả)
Đáp số : 84 quả cam
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2 câu đầu của bạn như bạn này mik giải rồi nhá
https://olm.vn/hoi-dap/detail/6617747567939.html
+) \(P=\dfrac{\left(a+b\right)^2\left(b+c\right)^2\left(c+a\right)^2}{\left(c+ab\right)\left(a+bc\right)\left(b+ca\right)}\)
\(=\dfrac{\left(a+b\right)^2\left(b+c\right)^2\left(c+a\right)^2}{\left(c\left(a+b+c\right)+ab\right)\left(a\left(a+b+c\right)+bc\right)\left(b\left(a+b+c\right)+ca\right)}\)
\(=\dfrac{\left(a+b\right)^2\left(b+c\right)^2\left(c+a\right)^2}{\left(c^2+ab+bc+ca\right)\left(a^2+ab+bc+ca\right)\left(c^2+ab+bc+ca\right)}\)
\(=\dfrac{\left(a+b\right)^2\left(b+c\right)^2\left(c+a\right)^2}{\left(a+b\right)^2\left(b+c\right)^2\left(c+a\right)^2}=1\)
+) \(M=\dfrac{1}{ab+a+1}+\dfrac{1}{bc+b+1}+\dfrac{1}{ca+c+1}\)
\(=\dfrac{1}{ab+a+1}+\dfrac{abc}{bc+ab^2c+abc}+\dfrac{abc}{ca+c+abc}\left(vìabc=1\right)\)
\(=\dfrac{1}{ab+a+1}+\dfrac{abc}{bc\left(ab+a+1\right)}+\dfrac{abc}{c\left(ab+a+1\right)}\)
\(=\dfrac{ab+a+1}{ab+a+1}=1\)
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123 x 456 + 123 x 543 + 123
=123 x 456 + 123 x 543 + 123 x 1
=123x(456+543+1)
=123x1000
=123000
102 x 178 - 102 -102 x 77
=102x(178-77)-102
=102x101-102
=10302-102
=10200
Bài giải
123 x 456 +123 x 543 +123
=123 x (456 + 543)
=123 x 999
=122 877
102 x 178 -102 -102 x 77
=102 x (178 - 77)
=102 x101
=10 302
\(3\left(x-\dfrac{1}{2}\right)-5\left(x+\dfrac{3}{5}\right)=-x+\dfrac{1}{5}\\ \Rightarrow3x-\dfrac{3}{2}-\left(5x+3\right)=-x+\dfrac{1}{5}\\ \Rightarrow3x-\dfrac{3}{2}-5x-3=-x+\dfrac{1}{5}\\ \Rightarrow3x-5x+x=\dfrac{1}{5}+3+\dfrac{3}{2}\\ \Rightarrow-x=\dfrac{2}{10}+\dfrac{30}{10}+\dfrac{15}{10}\\ \Rightarrow-x=\dfrac{47}{10}\\ \Rightarrow x=\dfrac{47}{10}:-1\\ \Rightarrow x=\dfrac{47}{10}.-1\\ \Rightarrow x=-\dfrac{47}{10}\)